1. Field of the Invention
The present invention relates generally to a manufacturing method of a stator module, and more particularly to a stator module with protection structure and a manufacturing method of a fan of the stator module.
2. Description of the Related Art
It is known that various fans are widely applied to all kinds of devices or sites, for example, personal computers, servers, storage devices, communication apparatuses, power supplies, vehicle industries, industrial control instruments, medical equipments, shipping equipments, air-conditioners and other industrial apparatuses.
A conventional fan stator includes a silicon steel sheet assembly, multiple windings, a circuit board and other electronic components. These components are exposed to air in contact with the vapor or dust in the air. Therefore, short-circuit may take place to these components to cause damage thereof due to humidity. In some more serious cases, these components may burn out and fail. This will affect the operation of the electronic device.
Therefore, when applied to various devices and sites, it is necessary to prevent the stator and other electronic components in the fan from humidity and salty fog. Currently, there are four ways to protect the stator and other electronic components as follows:    1. Cover body protection. A cover body is used to enclose and seal the stator so as to prevent the stator structure from direction contact with air. In this case, the stator is isolated from humidity and salty fog. However, in practice, such protection has some shortcomings. The cover body is disposed between the stator and the rotor around the stator. This leads to increase of the distance between the stator and the rotor. That is, the gap between the silicon steel sheet assembly of the stator and the magnet of the rotor is increased. As a result, the magnetization and induction performance will be reduced to affect rotational power of the fan. Furthermore, the stator is sealedly enclosed in the cover body by means of adhesive dispensing or O-ring press fit. The adhesive dispensing process costs long time and it is hard to control the amount of the adhesive so that the adhesive is likely to spill. The lifetime of the O-ring is short. After a period of use, the O-ring tends to crack. Under such circumstance, the humidity and salty fog are easy to infiltrate into the cover body.    2. Cover body and sealing adhesive protection. In order to solve the above problem of the cover body and enhance the sealing performance of the cover body, a sealing adhesive is filled into the cover body to seal the stator and electronic components. However, in practice, such protection still has some shortcomings. The magnetization and induction performance will be still reduced to affect rotational power of the fan. Moreover, it takes long time to wait for solidification of the sealing adhesive. In addition, during solidification process, the adhesive will apply a stress to the electronic components due to thermal change. This is likely to cause malfunction of the electronic components. It is necessary to pay great attention to the surface mount technology (SMT) strength between the electronic components and the circuit board. Moreover, the cover body is positioned in the outermost position. After the sealing adhesive is filled into the cover body, it is impossible to check the condition of the sealing adhesive inside the cover body. In the case of improper filling, bubbles will exist in the adhesive. This leads to probability of infiltration. Moreover, after sealed by the adhesive, the heat dissipation effect of the windings and the silicon steel sheets and electronic components of the stator will be deteriorated. This will cause rise of temperature of the stator.    3. Sealing adhesive protection. Along with the advance of the sealing adhesive, the stator can be sealed without using any cover body. After the stator is covered by a mold, the adhesive is directly filled or injected into the mold to seal the entire stator. After the adhesive is solidified, the mold is removed, whereby the stator is sealedly enclosed in the adhesive body. However, in practice, such protection still has some shortcomings. There are still the above problems existing in the sealing adhesive. Moreover, the affection of the injection pressure and injection temperature onto the electronic components must be taken into consideration. In addition, after injected, it is impossible to check whether the components are displaced due to the injection pressure.    4. Coating protection. By means of coating or vacuum coating, the adhesive is uniformly coated on the outer surfaces of the stator and other electronic components so as to achieve moistureproof and waterproof effect. However, in practice, such protection still has some shortcomings. The coating coated on the stator and other electronic components is quite thin and is likely to be damaged by alien article in the manufacturing process or during transfer. Moreover, the material of the stator and other electronic components will affect the surface adhesion of the coating or deteriorate the adhesion effect thereof. At high temperature, the coating may blister and damage.